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Childhood Poverty: Effects on the Immune System

By Roberta Attanasio

Redness, heat, swelling, pain – these are the four well known signs of the inflammatory response. Although a bit uncomfortable, these signs let us know that our immune system is working hard to get rid of microorganisms or other harmful agents while repairing tissue damage. Once the job is done, the immune system goes back to its steady-state, ready to fight again whenever the need arises.

However, the inflammatory response itself can sometimes be damaging. One type of damaging response leads to the development of degenerative diseases, as for example diabetes, cardiovascular disease and cancer. This type of response – chronic inflammation – may be triggered by a variety of factors. and childhood poverty is one of them. Indeed, results from several studies carried out in the past few years indicate that low childhood socioeconomic status is linked to a variety of health problems in adult age.

Macrophage
Credit: Timothy Triche, National Cancer Institute

Gregory Miller and Edith Chen, both at The Center on Social Disparities and Health, Institute for Policy Research, Northwestern University, propose a novel, provocative model to explain the link between childhood poverty and health problems in adult age. The model includes social and physical pollutants that, together, enable childhood disadvantage to become embedded in the function of monocytes and macrophages, which represent two different maturation stages of the same cell type and play a major role in orchestrating the immune response.

Known examples of social and physical pollutants, also called “anthropogens“, are unstable family structures, unresponsive caregivers and neighborhood violence. In addition, low socioeconomic status children are likely to experience household crowding, inadequate nutrition, and more exposure to second-hand smoke, infectious microorganisms, and industrial pollutants.

According to the model, clearly articulated in a recent article entitled “The biological residue of childhood poverty” and published in the journal Child Development Perspectives,  these pollutants enable disadvantage to become embedded in the function of monocytes and macrophages – in other words, because exposure to pollutants occurs during a sensitive period of immunological development, these cells acquire a pro-inflammatory phenotype, and this phenotype persists across the lifespan.

Thus, childhood poverty induces persistent inflammation, which is known to foster pathogenic changes that lead to degenerative diseases. According to the model, such process is reinforced by the acquired resistance of monocytes and macrophages to anti-inflammatory signals. Furthermore, early childhood disadvantage not only promotes a pro-inflammatory phenotype, it also gives rise to a behavioral predisposition that continuously accentuate this tendency.

In conclusion, Miller and Chen propose that childhood disadvantage leaves an “immunologic residue“. This immunologic residue manifests in pro-inflammatory responses and resistance to anti-inflammatory signals. It should be noted, however, that the research at the basis of this model is based on children that live in high income Western countries. In developing countries, where poverty is more common and extreme, the pathways of vulnerability may be different.

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Author: Roberta Attanasio

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14 Comments

  1. This blog poses a very interesting correlation between economic status and health that many including myself were not aware of. It would be quite interesting to observe the results from a study done in developing countries. Since some of these countries do not have heavy pollutants in the environment, would they still suffer the same disadvantage of resistant pro-inflammatory cells? There has been a documented increase in neonatal death from various infections in developing countries however the concern is still to be determined whether it is stemming from these environmental pollutants or a lack of efficient healthcare or education on the urgency of seeking medical attention.
    http://www.ncbi.nlm.nih.gov/pubmed/19106760

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  2. The relationship between childhood poverty and chronic inflammation in adulthood is something that I hadn’t considered much until now. I knew that things like poor nutrition, low quality material environment, or an unstable family life during childhood could manifest later on in life in the form of chronic health issues. However, I was not aware that they could affect the immune system on the cellular level (becoming embedded in the function of macrophages and monocytes).
    I also admit that I did not realize just how important your childhood is to all aspects of your health in adulthood. I found this post very informative, and was left with some questions. This inspired me to do some further reading, and I found a review article entitled “Poverty Grown Up: How Childhood Socioeconomic Status Impacts Adult Health” by K Conroy, M Sandel, and B Zuckerman. It focused on three different factors affecting adulthood outcomes: a child’s material environment, his or her social environment, and the structural or community environment. It brings up some of the points mentioned in this post, discussing childhood nutrition and environment and later health implications. One thing that I found particularly interesting was that this review article discussed research showing that the intrauterine environment also has lasting effects on adult health. Specifically, the authors discuss findings showing that intrauterine factors are associated with increased risk of type II diabetes, hypertension, and adult obesity, independent of adult-level risk factors for these health problems. It’s incredible how important childhood, infancy and even fetal environment are for adulthood, and how long-lasting the effects of anthropogens are.

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  3. Wealth and health are unnaturally correlated; health disparities between different socioeconomic groups have distinct impacts on health status. This blog post does a good job explaining the relationship between child poverty and the functionality of macrophages and neutrophils in the immune system. I imagine that children of lower socioeconomic status also suffer from chronically elevated cortisol levels. Cortisol is the stress hormone of the body, and in reasonable circulating amounts, it contributes to normal body functions. However, when chronically elevated, cortisol hinders the proliferation of T-cells, compromising the adaptive immune response. Cortisol also contributes to the atherosclerotic plaques that are associated with common cardiac pathologies such as hypertension.

    There is a great documentary called “Unnatural Causes” that addresses social disparities between different socioeconomic statuses. It can be found at: http://www.unnaturalcauses.org/episode_descriptions.php

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  4. I thought this article was very interesting and relevant considering the increasing numbers of children living in poverty in developed countries each year. I never really considered how the socioeconomic status of a child could affect the development of their immune system and later lead to lifelong illnesses. A child that is exposed to the many anthropogens that poverty introduces is at an unfair disadvantage and will have to live with the consequences of poor health for the rest of their lives. It is unfortunate that these children at a crucial state in the development of their immune systems do not have a chance at overcoming illnesses which could develop in to degenerative diseases. I found it interesting that a major component that leads to the chronic inflammation in children living in poverty is the inability of immune cells to respond to anti-inflammatory signals. I also wonder if there could be any type of vaccine or supplement that could be given to older children that have grown up in these conditions to fix this defective response or possible boost the immune cells so chronic inflammation would not be a lifelong condition.

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  5. I am not surprised to find that, indeed, there is a correlation between childhood poverty and the immune response. There have many hypotheses about the influence of the social environment in the early years on the biology of a person. Lam et al showed that there is a relationship between childhood poverty and the DNA methylation of genes. DNA methylation changes gene expression by switching genes on and off. Therefore I suspect that the genes influencing the function of monocytes and macrophages are negatively affected to cause chronic inflammation. In a chronic disease such as atherosclerosis, monocytes and macrophages play a key role in secreting pro-inflammatory factors as well as cytotoxic factors.
    Source: http://www.pnas.org/content/early/2012/10/04/1203167109.full.pdf+html, http://www.ncbi.nlm.nih.gov/pubmed/23886694

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    • This article was very interesting. I’m sure that in addition to atherosclerosis, the risk of other conditions would be increased as a result of chronic inflammation as well. In the innate immune response, activated macrophages also release reactive oxygen species (ROS). These molecules are highly reactive and allow for proper cell signaling as well as maintenance of homeostasis. However, increased ROS levels can cause oxidative stress. Oxidative stress results in disruptions in normal cell signaling and can lead to cancer, heart conditions, Alzheimer’s disease, Parkinson’s disease, and even autism. This goes hand in hand with the post by Christina K as well that mentioned a cytokine storm resulting in a higher risk of autism in children. Chronic inflammation can be very detrimental to the body and lead to higher risk of several diseases.

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  6. I found this article quite interesting because I was not aware that childhood poverty induces persistent inflammation. I was interested to see in what other circumstances you could see pro-inflammatory responses. In the article, “Pro-Inflammatory Phenotype Induced by Maternal Immune Stimulation during Pregnancy” by Nicholas M. Ponzio, et. al. researched mothers with autistic children and found a large increase in pro-inflammatory cytokine gene polymorphisms. As a result continuously stimulate the immune system by initiating several cytokines. The over stimulation can result in a cytokine storm which can sometimes be fatal. I found this interesting because this article relates back to the article “Autism and Air Pollution Go Together” (http://theglobalfool.com/autism-and-air-pollution-go-together/). This brings us back to the main idea that normally in areas of poverty, there are a larger amount of air pollution compared to areas without poverty. It is unfortunate to see the immune system working against us in rare cases and help with developing degenerative diseases.

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  7. This is a great point that I have never thought about, and it has stimulated my curiosity to dig deeper, and discover how circumstances that cannot be control by this innocents kids expose them to such inevitable tragedy. Unfortunately, it is one, as vulnerable as they are already, they did not ask for it, nor cause it; however, they may have to live with the consequences of poverty for the rest of their life.
    As, I come accross multiple articles reinforcing the Long-term Effects and consequences of Early Childhood Poverty, my hearth goes out to them as a parent.
    Interestingly as mentioned by “Ivy O”, i found that overactivation of the innate immune sytem may lead to chronic inflammation
    However, I am wondering if their immune system should not be stronger as preexposition to these anthropogen should prepared them better in the future should the same circumstance reemerge.
    When innate immunity failed, the adaptive, if properly functional, should be able to take over the course of the infection.
    If that it is not the case, should we then speculate that childhood poverty may lead to the impairment of the immune system?
    This is a very good article that may open more points for research and studies.

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  8. Related to what was mentioned above, I found a journal article that looked at childhood socioeconomic status and chronic inflammation. IL-6 production was used as a measure of the level of innate immune response, which was based on the idea that the cause of chronic inflammation can be over-activation of the innate immune system. While it’s no surprise that children who start out life at a disadvantage will often experience more sickness throughout life, it’s always good to have the research to back up this idea. The researchers found that children in a low socioeconomic class experienced twice the level of innate immune response versus those in a high socioeconomic class, with overweight children experiencing an even greater response. On the positive side, if the child’s socioeconomic class rose, their innate response decreased to that of a high socioeconomic class child. This latter result greatly supports the need for better poverty intervention in the lives of young children. (Source: Azad. Influence of Socioeconomic Status Trajectories on Innate Immune Responsiveness in Children. PLoS One. 2012)

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  9. Wow, the term “childhood poverty” just makes my heart beat faster. I know it’s hard to believe but I have lived among childhood poverty. I remember mothers with abusive husbands waking up early in the morning, filling the baby’s feeding bottle with some liquid that looked white and leaving to work in rubber plantations. This white liquid looked like milk and babies drank it not knowing it’s just “rice water”. Now rice water is all these moms can afford. Probably rice water has some benefits but of course it does not have all the nutrition that is in milk. And yes these babies as they grow are more prone for respiratory infections, protein energy malnutrition, and even physical deformities. Maintaining hygiene is hard for them too. Sometimes it’s partly due to ignorance but mostly it’s due to not having anything. I have two cousins who are affected with polio, still can’t walk and they are in their late twenty’s now. I totally agree.

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  10. Very interesting article. I never really thought about how environmental and economical pressures could cause an adverse affect on the immune system of young children. I do know for a fact that the poor are most likely to become ill compared to the wealthy; probably due to the in-ability to obtain health care. Let’s take Africa for example. The HIV rate in the country is extremely high. The virus can spread to the unborn baby across the placenta or via breast feeding. Which is an major issue because sometimes breast feeding can be the only food source available for the infant. But HIV antiviral drugs such as AZT is often used to prevent fetus infection (http://www.niaid.nih.gov/topics/hivaids/understanding/population%20specific%20information/Pages/children.aspx?, that is, if the patient can afford it. Children with HIV are exponentially more susceptible to environmental diseases than infected adults. One main reason is because they haven’t been exposed to various disease causing pathogens as infected adults have and second, their immune system has been crippled since birth. Poverty along with malnutrition definitely doesn’t do the immune system any justice and make it extremely hard for the body to produce CD4+ cells and other white blood cells to fight off an infection.

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    • To Stefon G: Your point about the inability to obtain health care is excellent. May be inability to obtain health care should be added to the list of anthropogens or social and physical pollutants, however we want to call them.

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    • Stefan G:

      Your points about lack of healthcare and poverty/HIV rates in Africa make a lot of sense but I wonder if the same things reign true for tribal communities. As the article mentioned, this study was conducted within low socioeconomic western societies. I can see the same results being found in the big African cities but I would like to know what the results would be among the indigenous groups. For all intents they would be considered low income groups, lack healthcare, and lack “proper nutrition”. However, they have managed to persevere through the ages. I wonder if those factors effect children substantially more in developed and/or developing countries/areas??

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  11. This story is very interesting, but I think what gives novelty to the concept is that it is seen under a different point of view (may be social/psychological/behavioral?) as compared to the biological one. It seems to me that, as the post author correctly states, these social and physical pollutants are anthropogens. So, in a sense, the concept is not new, anthropogens are already considered inducers of chronic inflammation and degenerative diseases (I first read about it in this same blog). But it’s interesting to think about it in terms of poverty, clearly poverty leads to a lifestyle that gives more chances to encounter anthropogens.

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